Could we finally be on the brink of understanding how the Scarecrow from The Wizard of Oz walked, talked, and generally did all sorts of things that require a brain, without actually having a brain? Perhaps not — some secrets of the Land of Oz are meant to stay forever mysterious. But back in the real world, researchers at AMOLF have pulled off a similar feat in the world of soft robotics. They have developed a small robot that can walk, swim, and jump, all without a “brain.”
The key to the robot’s locomotion is soft, elastomeric tubes with kinks in them. The tubes are supplied with a continuous flow of air that passes through them. The kink in the tube is able to move along its entire length, and depending on where it is, it restricts the outflow of air by closing the opening at the end of the tube to different extents. That, in turn, causes the tubes to undergo self-regulating, periodic motions that tend to synchronize with one another.
Humans for scale (📷: AMOLF)
On their own, these tubes behave chaotically — similar to those floppy, inflatable dancers often seen at car dealerships. But when several of them are coupled together, a surprising thing happens: order emerges. Their oscillations begin to synchronize spontaneously, resulting in rhythmic and coordinated movement without any central control. The robot takes off, moving in a steady gait across land or water, powered by nothing more than air and physics.
With no electronics, sensors, or software, the robot is quite simple, but that does not mean it is not capable. It has been demonstrated to reach speeds of up to 30 body lengths per second, which even surpasses the relative speed of a Ferrari, which clocks in at about 20. This is a significant leap beyond the performance of other air-powered robots, which often require centralized processors for coordination.
The robot is not just a speed demon, however, it is also highly adaptable. When it encounters obstacles or shifts between different environments, like land and water, its movement pattern automatically changes. On land, the legs hop in unison, but in water, its gait transitions to a freestyle swimming motion. This happens entirely through mechanical feedback between its body and surroundings.
The work is still in the very early stages, but the researchers envision future applications that could include drug-delivering microrobots that navigate the human body without electronics, energy-efficient exosuits that walk in step with users, or autonomous machines designed for harsh environments like space.